Audio mixer



FIG. 1 is a front, top and right side perspective view of an audio mixer showing our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is a right side elevational view; and

FIG. 7 is a left side elevational view. 

The ornamental design for an audio mixer, substantially as shown and described. 